Broadband vibrational energy harvesting

Abstract

A system that converts environmental vibrational energy into electrical energy includes a transducer that undergoes oscillating movement in response to the vibrational energy in order to produce an oscillating electrical signal. Power electronics process the oscillating electrical signal. A control system (including at least one control element of the power electronics, at least one sensor and control electronics) carries out a control scheme that dynamically varies the dampening of the oscillating movement of the transducer over time. The control scheme is based upon a predetermined parametric relation involving a plurality of variables derived from the properties measured by the at least one sensor. In several embodiments, the plurality of variables includes a first variable representing excitation frequency of the transducer. In another embodiment, the predetermined parametric relation represents relative phase between two variables derived from the properties measured by the at least one sensor.

What is claimed is: 
     
       1. A system for converting environmental vibrational energy into electrical energy for storage in at least one electrical power storage device, the system comprising:
 a transducer that undergoes oscillating movement in response to the environmental vibrational energy, the transducer producing an oscillating electrical signal in response to the oscillating movement; 
 power electronics, operably coupled between the transducer and the at least one electrical power storage device, the power electronics processing the oscillating electrical signal produced by the transducer, wherein the power electronics includes at least one control element having a configuration that provides variable dampening of the oscillating movement of the transducer in response to at least one control signal supplied thereto; 
 at least one sensor for measuring properties of the oscillations of the transducer over time; and 
 control electronics operably coupled to the at least one control element of the power electronics and to the at least one sensor, the control electronics carrying out a control scheme that generates and supplies the at least one control signal to the at least one control element over time in a manner that controls the at least one control element to dynamically vary the dampening of the oscillating movement of the transducer over time, wherein the control scheme is based upon a predetermined parametric relation involving a plurality of variables derived from the properties measured by the at least one sensor, wherein the plurality of variables include a first variable representing excitation frequency of the transducer. 
 
     
     
       2. A system according to  claim 1 , wherein:
 the plurality of variables further includes a second variable representing relative position of the transducer. 
 
     
     
       3. A system according to  claim 1 , wherein:
 the plurality of variables further includes a third variable representing relative velocity of the transducer. 
 
     
     
       4. A system according to  claim 1 , wherein:
 the plurality of variables further includes a fourth variable representing relative acceleration of the transducer. 
 
     
     
       5. A system according to  claim 1 , wherein:
 the plurality of variables further includes a fifth variable representing electrical current of the transducer. 
 
     
     
       6. A system according to  claim 1 , wherein:
 the plurality of variables further includes a sixth variable representing electrical voltage of the transducer. 
 
     
     
       7. A system according to  claim 1 , wherein:
 the predetermined parametric relation includes a term representing a damping factor for controlling the damping of the oscillating movement of the transducer, which results in the transducer force to be equivalent to the sum of a spring with a predetermined spring constant and a mechanical damper with a constant damping coefficient. 
 
     
     
       8. A system according to  claim 7 , wherein:
 the predetermined spring constant is configured such that the theoretical system resonance under the influence of a mechanical spring of the predetermined spring constant matches a particular off-resonant excitation frequency. 
 
     
     
       9. A system according to  claim 7 , wherein:
 the part of the term representing a spring with a predetermined spring constant is based on the plurality of variables, which include the first variable representing excitation frequency of the transducer, a second variable representing relative position of the transducer, and a third variable representing relative velocity of the transducer. 
 
     
     
       10. A system according to  claim 7 , wherein:
 the damping factor term is constrained by a lower bound, the lower bound greater than or equal to zero such that the damping factor term is always positive. 
 
     
     
       11. A system according to  claim 8 , wherein:
 the damping factor term is constrained by a lower bound, the lower bound less than zero such that the damping factor term can be both negative and positive. 
 
     
     
       12. A system according to  claim 1 , wherein:
 the predetermined parametric relation includes a term representing a damping factor for controlling the damping of the oscillating movement of the transducer, which results in the transducer force to be equivalent to the sum of a mechanical damper with a constant damping coefficient and a simulated mass. 
 
     
     
       13. A system according to  claim 12 , wherein:
 the simulated mass is configured such that the theoretical system resonance under the influence of an equivalent physical mass matches a particular off-resonant excitation frequency. 
 
     
     
       14. A system according to  claim 12 , wherein:
 the part of the term representing the simulated mass is based on the plurality of variables, which include the first variable representing excitation frequency of the transducer, a second variable representing relative velocity of the transducer, and a third variable representing relative acceleration of the transducer. 
 
     
     
       15. A system according to  claim 12 , wherein:
 the damping factor term is constrained by a lower bound, the lower bound greater than or equal to zero such that the damping factor term is always positive. 
 
     
     
       16. A system according to  claim 12 , wherein:
 the damping factor term is constrained by a lower bound, the lower bound less than zero such that the damping factor term can be both negative and positive. 
 
     
     
       17. A system according to  claim 1 , wherein:
 the parametric relation of the control scheme is configured to extend the bandwidth of oscillatory movements of the transducer that produce oscillating electrical signals by the transducer. 
 
     
     
       18. A system according to  claim 1 , wherein:
 the transducer comprises at least one coil and magnet that move relative to one another, wherein the at least one coil produces the oscillating electrical signal. 
 
     
     
       19. A system according to  claim 18 , wherein:
 the at least one control element of the power electronics comprises variable load circuitry operably coupled to the output of the at least one coil. 
 
     
     
       20. A system according to  claim 1 , wherein:
 the transducer comprises at least one piezoelectric element that produces the oscillating electrical signal. 
 
     
     
       21. A system according to  claim 20 , wherein:
 the at least one control element of the power electronics comprises variable load circuitry operably coupled to the output of the at least one piezoelectric element. 
 
     
     
       22. A system according to  claim 1 , wherein:
 the transducer and power electronics are configured to convert environmental vibrational energy into electrical energy, wherein the environmental vibrational energy is caused by fluid flow through a subterranean well or by drilling operations in a subterranean well. 
 
     
     
       23. A system for converting environmental vibrational energy into electrical energy for storage in at least one electrical power storage device, the system comprising:
 a transducer that undergoes oscillating movement in response to the environmental vibrational energy, the transducer producing an oscillating electrical signal in response to the oscillating movement of the transducer; 
 power electronics, operably coupled between the transducer and the at least one electrical power storage device, the power electronics processing the oscillating electrical signal produced by the transducer, wherein the power electronics includes at least one control element having a configuration that provides variable dampening of the oscillating movement of the transducer in response to at least one control signal supplied thereto; 
 at least one sensor for measuring properties of the oscillations of the transducer over time; and 
 control electronics operably coupled to the at least one control element of the power electronics and to the at least one sensor, the control electronics carrying out a control scheme that generates and supplies the at least one control signal to the at least one control element over time in a manner that controls the at least one control element to dynamically vary the dampening of oscillations of the transducer over time, wherein the control scheme is based upon a predetermined parametric relation representing relative phase between two variables derived from the properties measured by the at least one sensor. 
 
     
     
       24. A system according to  claim 23 , wherein:
 the two variables have a phase relationship of in-phase or 180 degrees out of phase in resonant vibrations, and the control scheme is configured to bring the two variables into a target phase relationship of in-phase or 180 degrees out of phase for cases, respectively, when the phase relationship of the two variables varies from the target phase relationship. 
 
     
     
       25. A system according to  claim 23 , wherein:
 at least one of the variables represents a time-varying characteristic of the transducer selected from the group consisting of: 
 i) excitation acceleration, 
 ii) excitation velocity, 
 iii) excitation position, 
 iv) relative acceleration, 
 v) relative velocity, 
 vi) relative position, 
 vii) electrical current, and 
 viii) electrical voltage. 
 
     
     
       26. A system according to  claim 23 , wherein:
 the control scheme includes first and second terms each representing constant damping factors for controlling the damping of oscillations of the transducer, wherein the first term represents a constant damping factor less than the constant damping factor represented by the second term. 
 
     
     
       27. A system according to  claim 26 , wherein:
 the control scheme selects the constant damping factor of one of the first and second terms based upon a measure of the phase relationship of the two variables. 
 
     
     
       28. A system according to  claim 27 , wherein:
 the measure of the phase relationship of the two variables is derived by multiplying the two variables. 
 
     
     
       29. A system according to  claim 23 , wherein:
 the parametric relation of the control scheme is configured to extend the bandwidth of oscillations of the transducer that produce oscillating electrical signals by the transducer. 
 
     
     
       30. A system according to  claim 23 , wherein:
 the transducer comprises at least one coil and magnet that move relative to one another, wherein the at least one coil produces the oscillating electrical signal. 
 
     
     
       31. A system according to  claim 30 , wherein:
 the at least one control element of the power electronics comprises variable load circuitry operably coupled to the output of the at least one coil. 
 
     
     
       32. A system according to  claim 23 , wherein:
 the transducer comprises at least one piezoelectric element that produces the oscillating electrical signal. 
 
     
     
       33. A system according to  claim 32 , wherein:
 the at least one control element of the power electronics comprises variable load circuitry operably coupled to the output of the at least one piezoelectric element. 
 
     
     
       34. A system according to  claim 21 , wherein:
 the transducer and power electronics are configured to convert environmental vibrational energy into electrical energy, wherein the environmental vibrational energy is caused by fluid flow through a subterranean well or by drilling operations in a subterranean well.